Preserve Host header as X-Forwarded-Host

[ajbouh]

I'm trying to use Ambassador to authenticate requests based on the Host header of an incoming request.

The current header overwriting policy means that I lose this information.

It seems like copying the value of Host over to X-Forwarded-Host might be the right thing to do.

The other X-Forwarded headers, like X-Forwarded-For and X-Forwarded-Proto may also be worth setting, though they aren't part of my specific use case.